Abstract

Background

The independent prognostic value of Circulating Tumour Cells (CTC) level has been demonstrated in patients with advanced breast, prostate and colorectal cancers. There is currently few data on Malignant Pleural Mesothelioma (MPM) and CTC. We investigated whether the presence of CTC was correlated with prognosis factors and treatment efficacy in MPM patients.

Methods

Patients (pts) with MPM in progression were enrolled before any new line of treatment in a prospective monocentric study. CTC detection was made on peripheral blood samples (7.5ml) using the “CellSearch” assay according to the manufacturer's protocol. The correlation between the presence of CTC and known worse prognosis factors was assessed using the X2 test. Progression Free Survival (PFS) was defined as the time from diagnosis until first progression (PFS1) and as the time from CTC measure until progression or death (PFS2). Comparison of PFS according to CTC detection was performed using the log-rank test. The cut-off date of the analysis was May 2012.

Results

Twenty-five MPM pts with a median follow-up of 4.2 months were included. The median age and sex ratio (M/F) were 65 years old and 2.1 respectively. Eighty-four percent of pts had an epithelioid MPM, 64% had a stage 4 disease, 60% had an anemia, a thrombocytosis or a leucocytosis at the time of inclusion. All pts except one had an Eastern Cooperative Oncology Group performance status (ECOG) < 2 and 64% received more than one line of chemotherapy. CTC were detected in 48% of pts (n = 12) with a median level of 1.5 (0-36). No significant correlation was observed between the presence of CTC and a metastatic disease, an ECOG ≥ 1, the presence of anaemia, leucocytosis, or thrombocytosis and the non-epithelioid type. The median PFS (1 and 2) were 17.9 (95%CI= [10.1-24.0]) and 2.5 (95%CI= [1.3-3.5]) months respectively. CTC detection was not a significant predictor of PFS 2 (p = 0.27).

Conclusion

Detection of CTC has been done in a small cohort of MPM patients. It could be an important tool though we were not able to demonstrate a significant prognostic value or a difference in PFS between CTC levels. The "Cellsearch" assay might not be the best technique to use in this setting. Further analyzes are in progress, and updated results will be presented in September.